R stats: not recognising 'F' as 'FALSE'

A student noticed that passing 'F' for 'FALSE' did not have an effect when
using functions in the stats base package.

Example:

pt(q=1.12, df=12, lower.tail=TRUE)

[1] 0.8576851

pt(q=1.12, df=12, lower.tail=F)

[1] 0.8576851

pt(q=1.12, df=12, lower.tail=FALSE)

[1] 0.1423149

I couldn't replicate the problem. Re-installing and updating R on their
machine had no effect. Does anybody know what could be causing this?

sessionInfo():
R version 3.2.2 (2015-08-14)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.11 (El Capitan)

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets
[6] methods   base

loaded via a namespace (and not attached):
[1] tools_3.2.2

Stats package:
Package: stats
Version: 3.2.2
Priority: base
Title: The R Stats Package
Author: R Core Team and contributors worldwide
Maintainer: R Core Team <R-core at r-project.org>
Description: R statistical functions.
License: Part of R 3.2.2
Built: R 3.2.2; x86_64-apple-darwin13.4.0

Liam